Oseltamivir Phosphate

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Cat Number

API204255118

CAS Number

204255-11-8

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CAS Number

204255-11-8

EINECS

616-396-9

Storage

Store at room temperature

Synonyms

Tamiflu; Oseltamivir phosphate; Oseltamir Phosphate; Agucort; 1-Cyclohexene-1-carboxylic acid, 4-(acetylamino)-5-amino-3-(1-ethylpropoxy)-, ethyl ester, (3R,4R,5S)-, phosphate (1:1)

Molecular Formula

C16H31N2O8P

Molecular Weight

410.4

Smiles

CCC(CC)O[C@@H]1C=C(C[C@@H]([C@H]1NC(=O)C)N)C(=O)OCC.OP(=O)(O)O

Appearance

White to yellowish-white powder

Melting Point

193-198℃

Relative Density

1.08

General Description

Oseltamivir phosphate is an oral neuraminidase inhibitor approved for the treatment and prophylaxis of influenza A and B virus infections. It is a prodrug that is rapidly converted to its active metabolite following oral administration.

Mechanism of Action

After conversion to oseltamivir carboxylate, the drug competitively inhibits the viral neuraminidase enzyme, which is essential for cleaving sialic acid residues from host cell surfaces. This blockade prevents the release of newly formed virions from infected cells, halting viral spread within the respiratory tract. The active metabolite is selective for influenza neuraminidase with minimal effects on human enzymes. Resistance can arise through H275Y mutations in the viral genome.

Application

Oseltamivir is indicated for the treatment of acute uncomplicated influenza in patients aged 2 weeks and older who have been symptomatic for no more than 48 hours. It is also approved for post‑exposure prophylaxis in adults and children aged 1 year and older.

In canine mammary cancer cells (CMA07, CMT‑U27), the anti‑influenza sialidase inhibitor oseltamivir phosphate impaired sialidase activity and increased overall sialylation, including α2,6‑linked terminal structures and SLeˣ. Surprisingly, oseltamivir stimulated CMT‑U27 cell migration and invasion in a dose‑dependent manner in vitro. In nude mouse xenografts, oseltamivir treatment led to increased lung metastases. The authors conclude that despite its antiviral utility, oseltamivir may increase mammary tumor aggressiveness by altering the sialylation pattern, raising a cautionary note for its use in cancer patients.

Fig. 1 Cell growth, cell viability and programmed cell death following oseltamivir treatment. (de Oliveira JT, et al., 2015)

References

de Oliveira JT, et al. Anti-influenza neuraminidase inhibitor oseltamivir phosphate induces canine mammary cancer cell aggressiveness. PLoS One. 2015;10(4):e0121590.

A Pickering water‑in‑oil emulsion was fabricated where molten glycerol monostearate crystallized at water droplet surfaces, forming protective solid shells. Sodium chloride, sodium citrate, and the anticancer agent oseltamivir phosphate were encapsulated as models. All actives showed near‑linear release over 30 days. Release could be modulated by adding Span 80 above its critical micelle concentration. Released oseltamivir significantly reduced viability of PANC‑1 pancreatic cancer cells for up to 30 days. This injectable platform provides sustained release of small hydrophilic molecules for weeks to months.

Fig. 2 Formulation of W/O monoglyceride stabilized Pickering emulsions. (Wood K, et al., 2018)

References

Wood K, et al. Oseltamivir phosphate released from injectable Pickering emulsions over an extended term disables human pancreatic cancer cell survival. Oncotarget. 2018;9(16):12754-12768.

Does Oseltamivir Phosphate require protection from moisture during storage?

It is slightly hygroscopic but chemically stable under normal humidity. However, to maintain flowability and prevent caking, store in tightly sealed containers with desiccant.

What is the recommended storage temperature for Oseltamivir Phosphate?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which can accelerate hydrolysis of the ethyl ester group.

Is Oseltamivir Phosphate stable in oral suspension formulations?

Reconstituted suspensions have limited stability (typically 10 days under refrigeration). We provide detailed in-use stability data for various vehicles and storage conditions.

How is the impurity oseltamivir carboxylate (active metabolite) monitored?

This primary hydrolysis product is specifically quantified using a stability-indicating HPLC method, ensuring it remains within ICH limits.